Systems in which material is conveyed through an elongate tubular passage for discharge therefrom at distances therealong are known, for example, for distributing food to a number of animal feeding stations along the tube.
U.S. Pat. Nos. 2,914,023 to St. Pierre, 3,504,654 to Geerlings et al., 3,990,402 to Eriksson, 4,337,728 to Van Gilst et al., 4,513,687 to De Jong, 4,495,895 to Reeder and 4,722,301 to Strong all disclose feeding systems in which vertical drop tubes are disposed at spaced intervals along a conveying path to discharge food material therefrom to respective feeding stations. In such an arrangement, it should be appreciated that material being conveyed along the path falls into the first drop tube until it becomes filled. Only once this first drop tube nearest the food source is filled does the next drop tube inline being to receive food from the conveying path. While the volume of a drop tube can be used to meter the amount of material to be distributed at each feeding station, the sequential filling of the drop tubes can result in a significant wait between delivery of material to the first and last drop tubes of the system. Facilitating simultaneous delivery of food material to the feeding stations therefore requires closing off the drop tubes until they are all substantially filled, at which point their contents can be released.
As a result, there is a desire for a way to provide relatively quick and even discharge of material from a conveying passage at spaced intervals therealong.